According to the 1947 and 1949 Army-Navy Catalog of Medical Materiel, this litter was indeed produced under the Stock Number of 7-838-600 and the nomenclature of Litter, Poleless, Semirigid. To the best of knowledge, post-war produced examples are identical in construction to those made during WW2, but can be distinguished by their markings. The later models (post-1947) have the new Medical Department insignia (a Caduceus flanked with the letters "U" and "S").
When I was putting the Litters Article together, my good friend Roger Dean (docdean64 here on the Forum) kindly forwarded me some photographs of his Litter, Semirigid, and here they are. As you can see, this particular example also has the twist-type post fixtures. I know that a lot of reproduction vehicle canvases utilise this type of fixture, but whether or not they were indeed used for this application during WW2, I am unsure.
I hope this will help Bill, and good luck with your purchase!